1. Field of the Invention
The present invention relates to synthetic inorganic crystalline base exchange materials. More particularly, the invention relates to a process for synthesizing crystalline base exchange materials of specific crystal sizes and having high total exchange capacities and specific initial exchange rates which yield well-defined residual concentrations for the elements of Group II of the Periodic Table. It is important to note that the exchange kinetics of products produced in accordance with the present invention occur effectively at low concentrations of the base exchange material.
2. The Prior Art
Cation exchange materials, and their use in many areas, are well known in the art. While many products are known to possess exchange properties, alumino silicates of the zeolitic type are known to exhibit preferences for particular types or sizes of molecules so that they are highly suitable for separation and exchange purposes. For example, all or a portion of the sodium normally contained in a typical zeolite structure may undergo exchange with a number of various other cations.
At the present time there are a number of commercially available and known alumino-silicate crystalline base exchange materials which may be represented by the general formula: EQU M.sub.2/n O:Al.sub.2 O.sub.3 :XSiO.sub.2 :YH.sub.2 O
wherein M represents a cation; n represents the valence of the cation; X, the moles of the SiO.sub.2 ; and Y, the moles of the H.sub.2 O. Specific examples of synthetic aluminum silicates are disclosed in U.S. Pat. Nos. 2,882,243; 2,962,355; 3,010,789; 3,012,853; 2,882,244; and 3,130,007.
Notwithstanding the fact that there are such known and commercially available crystalline products, to a large extent processes for producing synthetic exchange products are of the batch type and are limited by the inherent disadvantages associated therewith. Efforts to develop commercially feasible continuous systems or economical batch-type systems have been seriously hampered by the formation of a gel structure during the reaction cycle. Because of the formation of the gel, very cumbersome and costly processing steps and equipment are required. Also, in such processes there may be a carry-over of the gel in the final crystalline product. The gel is an inert diluent and impurity which seriously reduces the specific or unit volume capacity of the product. There is no known method for separation of this gel contaminant. The present invention overcomes such disadvantages of the prior art.